1. Field of the Invention
The present invention pertains to a method and apparatus for inspecting the physical feature of manufactured articles, and in particular the presence and number of attachments or the like attached to the articles.
2. Prior Art
FIG. 1 is a plan view showing a top end (manufactured article) of a usual aluminum can. The top end, designated at 1, includes a top-end body 2 having a sector-shaped opening portion 4 surrounded by a weakened seam 3 and a tab ring (attachment) 5 securely fixed to the top-end body 2 by caulking, and is provided with lip beads 6 and 6 so as to sandwich the opening portion 4 therebetween.
When manufactured, the top end of the aforesaid construction is subjected to various inspections, which includes an inspection for the presence of the tab ring 5.
The inspection of the tab ring 5 has hitherto been conducted by making the operators check each top end 1 visually or by obtaining images of the top surface of the top end 1 with an area sensing camera and inputting the image signals to an image processing device to process the images.
However, the manufacturing number of top ends has increased rapidly due to a drastic increase in the demand for aluminum cans, and hence the operators tend to suffer from considerable burdens, thereby causing inspection errors easily.
Furthermore, in the inspection using image processing techniques, it takes much time to carry out the image processing, resulting in low efficiency of inspection. In addition, it has been difficult to install an automated inspection system in a high-speed manufacturing line.